I get this question a lot and the simple/not so simple answer is:  HEAD SPACE.   As we drink a cocktail or eat our dinner we experience flavor in a few different ways.  The reactions that happen in our mouth:  Taste, Texture, Temperature.  And the reactions that happen in our olfactory center (smell).  Our olfactory center is stimulated primarily by what our nose smells.  Since flavor is made up by as much as 90% aroma, what our nose smells seriously influences what we "taste".  When we drink and eat our nose comes very close to whatever we are about to eat or drink and sends a message to our brain about it.  The space between our food or drink and our nose is called "head space."   Head space is where the soul of the food or drink lives and edible fragrance fills that nearly empty space with dazzling smells that send excite the nose and send a clear message to your brain:  THIS IS DELICIOUS.